Rapidly formed stable and aligned dense collagen gels seeded with Schwann cells support peripheral nerve regeneration

Abstract

Objective. Gel aspiration-ejection (GAE) has recently been developed for the rapid production of dense, anisotropic collagen gel scaffolds with adjustable collagen fibrillar densities. In this study, a GAE system was applied to produce aligned Schwann cells within a type-1 collagen matrix to generate GAE-engineered neural tissues (GAE-EngNT) for potential nerve tissue engineering applications. Approach. The stability and mechanical properties of the constructs were investigated along with the viability, morphology and distribution of Schwann cells. Having established the methodology to construct stable robust Schwann cell-loaded engineered neural tissues using GAE (GAE-EngNTs), the potential of these constructs in supporting and guiding neuronal regeneration, was assessed both in vitro and in vivo. Main results. Dynamic mechanical analysis strain and frequency sweeps revealed that the GAE-EngNT produced via cannula gauge number 16 G (∼1.2 mm diameter) exhibited similar linear viscoelastic behaviors to rat sciatic nerves. The viability and alignment of seeded Schwann cells in GAE-EngNT were maintained over time post GAE, supporting and guiding neuronal growth in vitro with an optimal cell density of 2.0 × 106 cells ml-1. An in vivo test of the GAE-EngNTs implanted within silicone conduits to bridge a 10 mm gap in rat sciatic nerves for 4 weeks revealed that the constructs significantly promoted axonal regeneration and vascularization across the gap, as compared with the empty conduits although less effective regeneration compared with the autograft groups. Significance. Therefore, this is a promising approach for generating anisotropic and robust engineered tissue which can be used with Schwann cells for peripheral nerve repair.